Watch out! He is cutting in front of you from the right, from the blind side. From the lane that was marked as ending a long way back. Other cars merged in as instructed, but not him. He is bent on getting ahead. Getting there a car-length earlier means a lot to this guy. There isn't really space for his car in front of you, but he makes space. He makes space because you chicken out and hit the brake as he swerves. He is more aggressive than you which is why he is now in front of you. He throws a casual wave as if to thank you, to thank you for being a sap. You are mad at him and mad at yourself both. You frown and fume and mutter various characterizations for this man.